Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Reexamination Certificate
1999-12-09
2001-05-01
Barts, Samuel (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
Reexamination Certificate
active
06225502
ABSTRACT:
This application is an application under 35 U.S.C. Section 371 of International application No. PCT/FR98/01334, filed on Jun. 24, 1998.
The subject-matter of the present invention is the use of electron-depleted aniline for releasing hydrochloric acid present in a reaction mixture and [lacuna] process for displacing, at least partially, an aniline from its hydrochloride. It relates more particularly to a process for displacing, at least partially, an aniline from its hydrochloride.
There are numerous synthetic reactions in chemistry which give off hydrochloric acid. Among these reactions, some release hydrochloric acid without specific measures having to be taken to achieve this.
Other reactions involve amines or require the presence of bases and thus result in the formation of salts of hydrochloric acid and in particular of hydrochloride. It is reactions of this type which are targeted by the present invention.
The treatment of salts of hydrochloric acid is extremely expensive and results in discharges which are sometimes supposed to be polluting and are always subject to regulatory control.
Mention may be made, among the reactions targeted, of alkylation reactions [in the present description, ALK-yl is taken in its etymological sense of hydrocarbon-comprising residue of an ALK-ohol, with the alcohol (or ohol) functional group being ignored] on chalcogen atoms or on atoms from Group V-B (Periodic Classification of the Elements as published in the Supplement of the Société Chimique de France, No. 1, January 1966).
Mention may in particular be made of the reaction of alkyl chloride with carboxyl functional groups and with phenol functional groups, as well as with amino functional groups, reactions which are supposed only to take place in the presence of the basic form of the functional groups to be alkylated.
It is also appropriate to mention the reactions of acid chloride, and in particular of acyl chloride, with nucleophilic substrates and in particular the substrates carrying the functional groups and/or atoms mentioned above.
The decomposition of aniline hydrochlorides and more generally amine hydrochlorides has been described previously, but these techniques employ very high temperatures, generally far above 200° C., and these techniques require the use of crystalline or solid hydrochloride.
Furthermore, such techniques are expensive and are not applicable to molecules which are unstable or volatile under the conditions of the decomposition of the hydrochloride.
This is why one of the aims of the present invention is to provide a technique which makes it possible to release hydrochloric acid present in an organic medium in the form of the hydrochloride of certain anilines.
Another aim of the present invention is to provide a process of the above type which makes it possible to obtain dry hydrochloric acid.
Another aim of the present invention is to provide a process which makes it possible to release an aniline from its hydrochloride at the same time as a reaction which releases hydrochloric acid is carried out simultaneously.
Another aim of the present invention is to provide a process which makes possible the alkylation or the acylation of specific anilines present, at least partially, in the form of their hydrochlorides in the reaction mixture.
These aims, and others which will become apparent subsequently, are achieved by means of a process for displacing, at least partially, an aniline from its hydrochloride, the said aniline in the process being chosen from anilines with a conjugate acid exhibiting a pKa at most equal to 6 and the process comprising a stage in which a reaction mixture comprising the said hydrochloride, at least partially dissolved in a lipophilic medium, is subjected to a temperature at least equal to approximately 50° C. (in the present description, the term “approximately” is employed in order to emphasize the fact that, when the figure or figures the furthest to the right of a number are zeros, these zeros are positional zeros and not significant figures, unless, of course, otherwise specified), advantageously to approximately 70° C.
The reaction is carried out at a temperature at most equal to approximately 200° C., advantageously at most to 200° C. (three significant figures), preferably to approximately 180° C.
The lipophilic medium can be in particular a weakly polar solvent or one of the reactant in excess, in particular the said aniline, alone or dissolved in a weakly polar solvent.
According to the present invention, it is preferable for the said aniline to exhibit a pKa at most equal to 5, advantageously 4, preferably to 3.
The solubility in weakly polar media also plays a significant role in the implementation of the present invention. It is therefore desirable for the solubility of the hydrochloride of the said aniline in benzene to be at least sparingly soluble (&dgr; or d), advantageously at least soluble(s), preferably very soluble (v). The symbols are those used in the reference work
Handbook of Chemistry and Physics.
Furthermore, it is desirable for the lipophilic medium to be weakly miscible with water and to be sufficiently hydrophobic not to be miscible with water in any proportion. It is thus preferable for water to be able to dissolve only at most 10% of the solvent or that which is acting as solvent; this limit is advantageously at most 5%, preferably at most 2%, by mass, advantageously even in the presence of the substrate as third solvent.
It is likewise preferable for the solvent to be able to dissolve only at most 10% of water, advantageously at most 5%, preferably at most 2%, by mass, advantageously even in the presence of the substrate as third solvent.
The term “weakly polar solvent” should be understood as meaning a solvent with a dielectric constant [which changes comparatively little with temperature but which is advantageously measured at about 20° C.; reference may be made, for dielectric constant values, to the fourth edition of the work published by John Wiley and Sons, “Techniques of Chemistry; Organic Solvents, Physical Properties and Methods of Purification”, by John A. Riddick, William B. Bunger and Théodore K. Sakano] at most equal to approximately 10 (relative dielectric constant ∈) . This value of ∈ is valid for the main constituent of the solvent but it is preferable for the whole solvent to correspond to this constraint.
The maximum value of ∈ is advantageously at most equal to 10 (two significant figures), preferably to 5 (value of chlorobenzene).
According to the present invention, it is preferable for the main constituent of the solvent to be weakly basic, that is to say for its donor index or donor number to be at most equal to approximately 20, preferably at most equal to 20 (two significant figures). The lower limit does not have a critical nature.
Reference may be made, for the definition of the donor number, to the work by Christian Reinhardt,
Solvents and Solvents Effects in Organic Chemistry,
p. 19 (1988), which work gives, as definition, the negative of the enthalpy (−&Dgr;H, expressed in kilocalories/mol) of the interaction between the solvent and antimony pentachloride in a dilute dichloroethane solution.
However, when mixtures of different compounds are used as solvents, it may be advantageous for one of them, in a minor proportion, to exhibit a degree of basicity.
The solvents can be mixtures, including petroleum fractions. Naturally, under the operating conditions, the solvents must be inert with regard to the substrates and reactants used.
Preferred families of solvents are chosen from the group consisting of hydrocarbons, aromatic derivatives, ethers, esters and halogenated solvents.
Mention may be made, as paradigms of these families, as halogenated aliphatic derivatives, of dichloromethane, 1,2-dichloroethane or 1,1,1-trichloroethane, as aromatic derivatives, of toluene, and as halogenated aromatic derivatives, of chlorobenzene, as esters, of ethyl acetate and isopropyl acetate, as ethers, of tert-butyl methyl ether, as well as a
Roustan Alain
Tirel Philippe-Jean
Barts Samuel
Rhodia Chimie
Seugnet Jean-Louis
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